Computer data storage systems have grown from direct-attached storage, where one or more disk drives are coupled to a system bus, to the more recently developed, higher capacity network-attached storage and storage area network technologies. Such greater capacity systems also present higher reliability, and higher availability. Moreover, storage area networks or “SANs” provide infrastructure on which sophisticated storage solutions can be built. Benefits include the ability to share a large storage device across many servers or applications, as well as the ability to create arrays of multiple physical storage devices to present large storage capacities (e.g., terabytes). In such systems, host computers (e.g., servers) couple to the physical storage devices via networks or fabrics that may include one or more switches. Each switch may implement a plurality of ports, some of which provide for connection to one or more host computers and others of which provide connections to the storage devices.
A large physical storage capacity is often difficult to use efficiently. Configuring, maintaining, and backing up large storage volumes can be time-consuming. Also, it can be difficult to integrate large storage volumes into RAID arrays to obtain improved availability and reliability. To improve sharing such a large storage capacity amongst many host computers and processes, the storage is typically segregated into smaller pieces called logical units, which are then assigned to one or more host computers.
SANs can be complex systems with many interconnected computers, switches and storage devices, and this complexity can make it difficult for SAN administrators to troubleshoot a problem, particularly where the problem occurs as a connectivity issue, whether in or to the host computers, the switches, the storage devices themselves, or in or to the ports of the host computers, storage devices and/or the switching fabric, or in any of the physical interconnections therebetween, amongst other possible sources of error. Thus, a benefit may accrue to SAN administrators upon the provision of a simplified way to confirm connectivity across a network, and to isolate the reason or reasons for a particular connectivity failure if they find a lack of connectivity. Physical connections and the configurations of multiple devices can all contribute to a connectivity failure. The SAN administrator must determine which cause or causes are at fault on the many possible paths between one side of the network and the other. In addition, SAN administrators may select appropriate objects (e.g., host computers, switch ports and storage devices) to connect to each other. The more a SAN administrator knows about the state of the network, and the possible paths between end objects, the easier it is to select objects that will require a minimum of effort to connect successfully. And additionally, to maintain security of the data and optimal performance of the network, the administrator must prevent unauthorized or unintended connectivity, or eliminate such connectivity if it can be detected.
In the past, SAN administrators have had to physically inspect the end-to-end cable paths and then invoke multiple software applications to record and view the configurations on multiple devices to determine the cause or causes of a connectivity failure. This has involved steps of reviewing multiple event logs, and/or maintaining complicated spreadsheets to try to isolate the source of a problem. This work is especially time consuming if there really is no network connectivity problem and the network administrator is called upon to “prove a negative,” by showing that there are no failures or wrong configurations in the network. Network administrators have also used spreadsheets to maintain relevant pieces of data, often on separate sheets, to determine which objects are the best candidates for connection. Only partial, or very cumbersome solutions, particularly in the form of a system, software and/or methods for software, data structures and/or systems for confirming connectivity in storage area network are currently available.